Sheet materials, such as tissue, are often sold in a dispenser that frequently comprises a paperboard carton. There are two common packaging formats that have found widespread usage in the tissue industry. These two formats include a “flat” tissue carton and an “upright or boutique” tissue carton. In the flat tissue carton, the tissue clip inside the carton is not folded but instead the clip is a flat stack of individually folded tissue sheets. Flat tissue cartons have a rectangular top and bottom and come in various heights depending on the sheet count of the tissue clip. In the upright tissue carton, the tissue clip is typically folded into a U-shape and then inserted into a carton. Upright tissue cartons have a square top and bottom and are generally cubical in shape.
In existing machines to load tissue clips into flat cartons, the clip is pushed from the end along the longitudinal central axis of the clip into the carton. In existing machines to load tissue clips into upright cartons, the clip is first folded into a U-shape and then pushed from the side along the clip's transverse central axis into the carton. Thus, the orientation of the clip with respect to the open end of the carton differs by 90 degrees when loading the clip into the carton for the two common dispensing formats.
Because the clip is first folded into a U-shape and then placed into the bucket, an upright cartoner's bucket conveyor for loading upright clips requires a larger distance or pitch between the individual buckets than a flat cartoner's bucket conveyor for loading flat clips into flat cartons. Consequently, this can reduce the cartoner's output rate since the maximum output rate is related to the linear velocity of the bucket conveyer. Therefore, to load the same number of cartons per hour, an upright cartoner must run at a faster bucket conveyer line speed than a flat cartoner. This faster speed can result in the folded clip's position skewing and shifting within the conveyor bucket, resulting in either waste and delay or improperly folded clips in the finished product cartons.
Consumer preference for the two dispensing formats is split approximately evenly so a manufacturer, to be competitive, must sell each dispensing format. There are several options for meeting this consumer demand. First, a manufacturer can simply purchase at least one packaging machine to load each carton style. There would be dedicated machines to handle flat cartons and other dedicated machines to handle upright cartons. However, if there is insufficient demand to use each installed packaging machine at full capacity, this can result in an expensive option for the manufacturer; especially, considering that high speed cartoners for upright cartons typically cost 25–40 percent more than high speed cartoners for flat cartons. As consumer demand changes between the two formats, the dedicated machine option is not very flexible to meet changing production schedules.
Second, the packaging machine can be grade changed as necessary to switch between the two carton formats. This requires stopping production and then many changeover parts must be either added or removed to reconfigure the machine for properly loading the clip into the other style carton. As previously discussed, the pitch between flat buckets and upright buckets can be different and the clip loading method into the bucket must also be changed. Thus, changing between the two formats is not a simple matter. This can result in expensive production downtime, extra costs and inventory for changeover parts, and qualified mechanics to reconfigure the machine each time a change is required. Additional machine time or reduced productivity can be lost while adjusting the packaging machine once the changeover is made to optimize the machine for the new carton format.
Third, a dual format packaging machine, as disclosed in U.S. Pat. No. 6,202,392 entitled Flexible Tissue Handling Apparatus issued to Greenwell et al. on Mar. 20, 2001, and herein incorporated by reference, can be purchased. To package flat cartons, extensible pushers turn the tissue clips 90 degrees so they drop into transverse channels. Subsequently, flat overhead tamps descend and the tissue clips are pushed through guide buckets into the end of the flat cartons. To package upright cartons, the extensible pushers are disengaged so the lengths of the tissue clips remain in the machine direction spanning the transverse channels. Subsequently, narrow tamps descend, pushing the center of the tissue clips into the transverse channels, forming the tissue clips into the beginning of a U-shape ready for pushing through guide buckets into the side of the boutique cartons. Generally, the clips in either case are received in individual buckets of a bucket conveyor, and, in the appropriate configuration, are loaded into cartons moving along a machine direction in phased relation to the buckets. A transfer guide bucket conveyor is typically interposed between the buckets and the cartons for receiving and guiding the configured clip as it is pushed transversely from the bucket into the carton.
This option, however, requires the purchase of expensive new machines to replace the previous packaging machines. Capital spending can have a long payback period in the highly competitive tissue business; especially, if the older packaging machines have been fully depreciated but still have acceptable production rates. Additionally, all the clips are initially placed with their longitudinal axis aligned in the machine direction which requires a larger distance between individual buckets and consequently reduces machine speed potential when loading flat cartons compared to a dedicated flat cartoner. Rotating the clip 90 degrees when running flat grades also limits the speed potential and can lead to increased waste and delay from the additional handling step. The clip can become twisted or otherwise diverge from its uniform stacked configuration during rotation and this can cause jamming of the machinery or lead to improperly loaded cartons.
Therefore, what is needed is a method and apparatus that can load both flat and upright cartons on the same packaging machine that requires a minimum of downtime when changing from one carton format to the next. Also, what is needed is a method and apparatus that is compatible with existing packaging machines, including high speed models, such that they can be easily converted into a flexible carton loading apparatus with a minimum of expense. Additionally, what is needed is an apparatus that can load flats and uprights with bucket spacing or pitch similar to a flat cartoner such that productivity when loading flats is not compromised and productivity when loading uprights is increased.